1. Field of the Invention
The present invention relates to an air-conditioning device for controlling the temperatures that are set in a room such as, for example, a passenger compartment in a first air-conditioning zone and in a second air-conditioning zone independently of each other.
2. Description of the Related Art
An air-conditioning device for controlling two or more different air-conditioning zones independently of each other has heretofore been known as represented by an air-conditioning device for automobiles disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 58-33509. In practice, automobiles employ an air-conditioning unit of a structure shown in FIG. 3 when the temperatures in the air-conditioning zone on the the driver's seat side and in the air-conditioning zone on the side of the seat next to the driver in the passenger compartment are to be controlled independently of each other.
That is, in FIG. 3, there are arranged a blower 3, an evaporator 4 and a heater core from the upstream side toward the downstream side in an air duct 2 that is equipped with an internal air/external air change-over damper 1 on the most upstream side, and the downstream side of the heater core 5 is divided by a partitioning wall 6 into an air-conditioning system 7 on the driver's seat side and an air-conditioning system 8 on the side of the seat, next to the driver.
On the upstream side of the heater core 5, there is provided an air-mixing damper 9 on the driver's seat side for adjusting the ratio of the amount of the air that flows into the air-conditioning system 7 on the driver's seat side passing through the heater core 5 and the amount of the air that flows into the air-conditioning system 7 by-passing the heater core 5. There is further provided an air-mixing damper 10 on the side of the seat next to the driver for adjusting the ratio of the amount of the air that flows into the air-conditioning system 8 on the side of the seat next to the driver passing through the heater core 5 and the amount of the air that flows into the air-conditioning system 8 by-passing the heater core 5.
On the most downstream sides of the air-conditioning system 7 of the driver's seat side and of the air-conditioning system 8 of the side of the seat next to the driver, there are provided foot blow-out ports 7a and 8a for blowing the conditioned air onto the feet of the passengers, face blow-out ports 7b, 7c and 8b, 8c on the center side for blowing the conditioned air to the faces and chests of the passengers, and a defroster blow-out port 11 for blowing out the conditioned air onto the front window pane. In the air-conditioning system 7 on the driver's seat side and in the air-conditioning system 8 on the side of the seat next to the driver are provided blow-out port change-over dampers 12 to 16 for selectively opening and closing the above blow-out ports 7aa to 7c, 8a to 8c and 11. By changing the opening degrees of these dampers 12 to 16, it is possible to obtain a predetermined blow-out port mode such as a foot mode, a bi-level mode, a fase mode or a defrost mode independently between the air-conditioning system 7 and the air-conditioning system 8.
Separate temperature setters are used to input a setpoint temperature Tset(Dr) for the air-conditioning zone on the driver's seat side that corresponds to the foot blow-out port 7a and the face blow-out ports 7b, 7c in the air-conditioning system 7 on the driver's seat side and to input a setpoint temperature Tset(Pa) for the air-conditioning zone on the side of the seat next to the driver that corresponds to the foot blow-out port 8a and face blow-out ports 8b, 8c in the air-conditioning system 8 on the side of the seat next to the driver. Here, however, the setpoint temperatures Tset(Dr) and Tset(Pa) must be determined by taking the temperatures inside and outside the passenger compartment of an automobile and the amount of solar radiation into consideration. In practice, furthermore, there exist air stream interference and temperature interference between the two air-conditioning zones, and the air blown into one air-conditioning zone and its temperature affect the temperature in the other air-conditioning zone. Therefore, a difference between the setpoint temperatures Tset(Dr) and Tset(Pa) must also be taken into consideration.
It can therefore be contrived to determine a target blow-out temperature TAO(Dr) on the driver's seat side and a target blow-out temperature TAO(Pa) on the side of the seat next to the driver through a calculation in compliance with the following equations (1) and (2), and to determine the opening degrees of the air-mixing dampers 9 and 10 of the driver's seat side and of the seat next to the driver side relying thereupon, as well as to determine the blow-out port modes of the air-conditioning systems 7 and 8 and the control voltage for the blower 3. EQU TAO(Dr)=K.sub.set .multidot.T.sub.set (Dr)-Kr.multidot.Tr-K.sub.am .multidot.T.sub.am -Ks.multidot.Ts+Kd(Dr) (T.sub.set (Dr))-T.sub.set (Pa))+C (1) EQU TAO(Pa)=K.sub.set .multidot.T.sub.set (Pa)-Kr.multidot.Tr-K.sub.am .multidot.T.sub.am -Ks.multidot.Ts+Kd(Pa) (T.sub.set (Pa)-T.sub.set (Dr))+C(2)
where Tr, Tam and Ts are an internal air temperature (temperature in the passenger compartment of an automobile), an external air temperature (temperature outside the passenger compartment of an automobile) and the amount of solar radiation entering into the passenger compartment of an automobile, Kset, Kr, Kam, Ks, Kd(Dr) and Kd(Pa) denote a temperature setpoint gain, an internal air temperature gain, an external air temperature gain, a solar radiation amount gain, and temperature difference correction gain between the air-conditioning zone on the driver's seat side and the air-conditioning zone on the side of the seat next to the driver, and C denotes a correction constant.
The opening degree SW(Dr)(%) of the air-mixing damper 9 on the driver's seat side and the opening degree SW(Pa)(%) of the air-mixing damper 10 on the side of the seat next to the driver are determined through calculations in compliance with the following equations (3) and (4). EQU SW(Dr)=(TAO(Dr)-TE).times.100/(TW-TE) (3) EQU SW(Pa)=(TAO(Pa)-TE).times.100/(TW-TE) (4)
where TW is a temperature of the engine cooling water that flows through the heater core 5, and TE is a temperature of the air after it has exchanged the heat with the evaporator 4.
The blow-out port modes of the air-conditioning systems 7 and 8 of the driver's seat side and of the seat next to the driver side are determined based upon the target blow-out temperatures TAO(Dr) and TAO(Pa), and upon predetermined target blow-out temperature vs. blow-out port mode characteristics shown in FIG. 4. That is, when the target blow-out temperatures TAO(Dr) and TAO(Pa) are relatively high, the foot mode (FOOT) is selected and when the target blow-out temperatures TAO(Dr) and TAO(Pa) are relatively low, the face mode (FACE) is selected. Furthermore, when the target blow-out temperatures TAO(Dr) and TAO(Pa) are between the above-mentioned states, the bi-level mode (B/L) is selected. Here, as will be obvious from FIG. 4, a predetermined differential is maintained between the target blow-out temperatures TAO(Dr), TAO(Pa) and the blow-out port modes.
Moreover, the control voltage VA for the blower 3 for determining the air blow rate is obtained by finding a control voltage VA(Dr) suited for the target blow-out temperature TAO(Dr) on the driver's seat side and a control voltage VA(Pa) suited for the target blow-out temperature TAO(Pa) on the side of the seat next to the driver based upon a relationship of FIG. 5, and then averaging these control voltages VA(Dr) and VA(Pa).
It is now presumed that the target blow-out temperatures TAO(Dr) and TAO(Pa) are 20.degree. C. in the case where the setpoint temperatures Tset(Dr) and Tset(Pa) are 25.degree. C., in a given environmental condition as shown in FIG. 6 which illustrates a change in the target blow-out temperature in response to a setpoint temperature. In this case, if the setpoint temperature Tset(Dr) on the driver's seat side is changed from 25.degree. C. into 28.degree. C. at a timing t1 with the setpoint temperature Tset(Pa) on the side of the seat next to the driver being maintained at 25.degree. C., the target blow-out temperature TAO(Dr) on the driver's seat side changes from 20.degree. C. into, for example, 50.degree. C., and the target blow-out temperature TAO(Pa) on the side of the seat next to the driver changes from 20.degree. C. into, for example, 11.degree. C. This change in the target blow-out temperature TAO(Pa) stems from the presence of a calculation term "Kd(Pa)(Tset(Pa)-Tset(Dr))" for correcting the temperature difference between the air-conditioning zone on the driver's seat side and the air-conditioning zone on the side of the seat next to the driver in the aforementioned equation (2).
However, even though the temperature difference between the right air-conditioning zone and the left air-conditioning zone has been controlled in the prior art, the effect of temperature of the external air upon the temperature of the conditioned air had not at all been taken into consideration causing a problem that is described below.
That is, it was clarified that a relationship between the external air temperature Tam and the control temperature ratio A becomes as shown in FIG. 8 in a state in which the setpoint temperature Tset(Pa) on the side of the seat next to the driver is maintained at 25.degree. C. constant as shown in FIG. 7, wherein .DELTA.T denotes an average difference between the air-conditioning temperatures T(Dr) and T(Pa) when the setpoint temperature Tset(Dr) on the driver's seat side is changed, and the ratio (.DELTA.T/.DELTA.Tset) of the above temperature difference .DELTA.T with respect to a change .DELTA.Tset in the setpoint temperatures Tset(Dr) and Tset(Pa) is called control temperature ratio A.
In an example of FIG. 8, the temperature control ratio A becomes "1" when the external air temperature Tam is 10.degree. C. and the air-conditioning temperature is not affected by the external air temperature Tam. When the external air temperature Tam is 30.degree. C., however, the control temperature ratio A drops. Therefore, when a state where the external air temperature is 10.degree. C. is compared with a state where the external air temperature is 30.degree. C., the practical temperature difference .DELTA.T between the air-conditioning zones decreases in the state where the external air temperature is 30.degree. C. In a state where the external air temperature Tam is -10.degree. C., the practical temperature difference .DELTA.T between the air-conditioning zones increases contrary to the above-mentioned case.
In short, when different temperatures Tset(Dr) and Tset(Pa) are set in the air-conditioning zones on the driver's seat side and on the side of the seat next to the driver, the practical difference in the air-conditioning temperature between the air-conditioning zones becomes smaller than a preset value in a state where the external air temperature is relatively high like in summer and the practical difference in the air-conditioned temperature between the air-conditioning zones become larger than a preset value in a state where the external air temperature is relatively low like in winter, causing the independence of the air-conditioning zones to be lost.